The specific aims of this work are; (1) to develop chiral Lewis acid catalysts based on substituted-monocyclopentadienylzirconium and substituted zirconocene complexes and; (2) to test the scope and selectivity of their reactivity with three reactions using reactants designed to test the ability of these catalysts to promote these reactions with varying substrates. These compounds will provide a useful tool to the synthetic organic chemist working on small or large scales by providing an atom efficient technique to prepare key intermediates or link different fragments to form the final product. These catalysts will perform (4+2) cycloaddition, addition to C+O double bonds and join alkene and carbonyl functionalities, reactions that are important in the synthesis of many natural products, drugs and drug candidates, including amino acids, DNA intercalators and anti-tumor agents. The catalysts or catalyst precursors will be prepared by a series of high yield reactions. They will be prepared in high selectivity form readily available starting materials in high yields. Yields in precursor synthesis are above 75% and are generally better. The system allows adjusting acidity by varying the combinations of cyclopentadienyl (from the strong donor pentamethyl- to the poor donor pentaphenylcyclopentadienyl) and different alkoxide or other auxiliary ligands. Our 4exptations that the substituted zirconocene complexes will undergo diastereo selective reaction with chiral alcohols or amines to give chiral-at-metal complexes is based on previous work with quite similar complexes. The monocyclopentadienyl complexes will form asymmetric expected that a single catalyst will perform all the reactions equally well: several "families" of catalysts are planned to find what ligand combinations are more effective. Reactivity will be screened by a series of substrates for each reaction to determine selectivity and efficiency (as measured by turnover frequency and turnover number). Analysis will be performed by spectroscopic or gas chromatographic methods.